Engineering disasters: Hyatt Hotel Walkway

On 17th July 1981 hundreds of people gathered in the lobby of the Hyatt Regency Hotel, in Kansas City, Missouri. The lobby was multi-storey, with concrete walkways crossing above the centre.

At just after 7 p.m. the lobby was packed with people who had come to watch and take part in a dance contest. The walkways were crammed with people trying to get a good view of the action.

Unfortunately, due to a structural fault with the walkways, they could not cope with the weight of so many people, and the fourth floor walkway collapsed. It fell onto the second floor walkway which, in turn, crashed to the floor.

The tragedy claimed over 100 lives and at the time was the deadliest structural collapse in U.S. history.

Why did it happen?

The walkways were suspended by steel tie rods. The fourth floor walkway was suspended from the ceiling, and the second floor walkway was suspended from the fourth.

The problem was simply that this meant there was too much weight on the beams supporting the fourth floor. The beams could support one walkway plus a load, but was not strong enough to support the second floor walkway too.

How would engineers fix it?

The problem and a solution were uncovered by Wayne Lischka, a structural engineer hired to investigate the disaster. He found that the original plans for the building had suggested the second floor walkway be connected to the ceiling rather than the fourth floor.

This would have meant that the fourth floor would not have had such a heavy load. Unfortunately it also meant that the steel ties which held the second walkway up would probably have been damaged during installation, so the idea was scrapped. This left a dangerously heavy load resting on the fourth floor walkway, which was only capable of holding 30 per cent of the suggested minimum weight.